Primary and Secondary Bonds

The secondary bonds are presumably due to the same nonspecific attractive forces which cause precipitation of globulins in the absence of salt or gelation of denatured proteins under certain controlled conditions —a combination of coulombic, dipole, hydrogen bond, and nonpolar attractions depending on the amino acid distribution concerned (Section c, page 63). 

Schematic illustration of proposed structure of the fine clot. From Ferry and Morrison (1947a). 

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It is because these primary and secondary bonds can form that matter condenses from the gaseous state to give liquids and solids. Five distinct condensed states of matter,... 

The scale of the microscopic surface roughness is important to assure good mechanical interlocking and good durability. Although all roughness serves to increase the effective surface area of the adherend and therefore to increase the number of primary and secondary bonds with the adhesive/primer, surfaces with features on the order of tens of nanometers exhibit superior performance to those with features on the order of microns [9,14], Several factors contribute to this difference in performance. The larger-scale features are fewer in number... 

Compounds containing susceptible C—H bonds can be oxidized to alcohols. " Nearly always, the C—H bond involved is tertiary, so the product is a tertiary alcohol. This is partly because tertiary C—H bonds are more susceptible to free-radical attack than primary and secondary bonds and partly because the reagents involved would oxidize primary and secondary alcohols further. In the best method, the reagent is ozone and the substrate is absorbed on silica gel. Yields as high as 99% have been... 

As an example he referred to "psuedo-high molecular weight" inorganic complexes. In a similar fashion, Pringsheim discussed the nature of inulin and other polysaccharides. Bergmann and Pringsheim cited the work of P. Karrer, K. Hess, and R. Pummerer and referred to primary and secondary bonding as proposed by Werner. 

Both synthetic and natural polymers have superstructures that influence or dictate the properties of the material. Many of these primary, secondary, tertiary, and quaternary structures are influenced in a similar manner. Thus, the primary structure is a driving force for the secondary structure. Allowed and preferred primary and secondary bondings influence structure. For most natural and synthetic polymers, hydrophobic and hydrophilic domains tend to cluster. Thus, most helical structures will have either a hydrophobic or hydrophilic inner core with the opposite outer core resulting from a balance between secondary and primary bonding factors and steric and bond angle constraints. Nature has used these differences in domain character to create the world around us. 

The size and shape of polymers are intimately connected to their properties. The shape of polymers is also intimately connected to the size of the various units that comprise the macromolecule and the various primary and secondary bonding forces that are present within the chain and between chains. This chapter covers the basic components that influence polymer shape or morphology. 

Fig. 8.5. T1+ coordination number versus anion bonding strength. The curved line represents the coordination number expected if the valence of the Tl-O bonds is equal to the anion bonding strength. The circles are observed coordination numbers. The vertical lines mark the primary coordination number (bottom arrows) and the total coordination number (top arrow) for environments that contain both primary and secondary bonds.

In the vast majority of cases in which six coordination is observed, the bonding can be viewed as arising from the interaction of all three cr -orbitals with a halide anion, i.e., all three in S. Because the three orbitals are all trans to the primary E-X bonds, such a situation leads naturally to octahedral coordination. Moreover, in cases in which the primary and secondary bonds are the same length, i.e., where A = 0 and a three-center, four-electron bonding model is appropriate, a regular octahedron is the result. Such a structure is clearly at odds with simple VSEPR theory, which is predicated on the lone pair(s) occupying specific stereochemical sites, but stereochemical inactivity of the lone pair tends to be the rule rather than the exception in six-coordinate, seven-electron pair systems Ng and Zuckerman (102) have reviewed this topic for p-block compounds in general. 

Sulfur as well as Se and Te form many compounds formally containing EX3 ions, with X = F, Cl, Br, or I. In all of these, however, there are strong secondary interactions between these cations and the accompanying anions so that the coordination numbers of the element E, counting both primary and secondary bonds, reaches 7, 8, and even 9. 

With the discovery of x-ray diffraction and the opportunity this gave to determine exactly where the atoms are in a crystal, there arose an unexpectedly direct way to ascertain the measure of reality behind the Werner theory and its implied equivalence of some primary and secondary bonds. 

The effective coordination number, indicating all mercury-ligand interactions that are less than the sum of their respective van der Waals radii, or simply the total number of primary and secondary bonds. 

The electronic structure of atoms determines the type of bond between the atoms concerned. As we said earlier, chemical bonds may be classified as primary or secondary depending on the extent of electron involvement. Valence electrons are involved in the formation of primary bonds. This results in a substantial lowering of the potential energies. Consequently, primary bonds are quite strong. On the other hand, valence electrons are not involved in the formation of seeondaiy bonds — leading to weak bonds. Primary and secondary bonds can be further subdivided ... 

Gelation of aqueous solutions of animal glues upon cooling is an important characteristic. Gelation involves both intra- and intermolecular reorientation upon cooling of the solution. It is caused by the formation of random primary and secondary bonds. Intermolecular network formation is primarily the result of a cross-linking mechanism between molecular chains by hydrogen bonds [11]. 

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